In conventional modern day washing machines of the top-loading type, there is typically provided an outer tub which holds the wash and rinse water.
Within the tub is disposed a perforate basket acting as a clothes-receiving receptacle and within the basket an agitator or impeller which is oscillated during the wash and sometimes during the rinse cycle in order to produce agitation and circulation of the clothing items in the water to produce thorough washing and rinsing action.
The basket is utilized to execute centrifugal extraction of the wash and rinse water from the clothing items during spin dry cycles. That is, the basket is rotated at a relatively high rate of rotation in order to cause centrifugal outward movement of the water from the basket into the outer tub. After being collected in the outer tub, the water is drained preparatory to initiation of another machine cycle.
The respective drives to the agitator and basket are commonly afforded by a transmission unit coupled to a single drive motor. The transmission in one mode produces high speed rotation of the basket for the spin cycle and in a reverse direction of rotation of the drive motor, a relatively slow speed oscillatory output of the transmission is created which is transmitted to the washing machine agitator to execute the necessary motion thereof.
The oscillatory output is commonly achieved by use of a mechanical movement which converts the unidirectional rotary motion of the drive motor into an oscillatory output of the agitator power shaft. The mechanical movement necessary is generally complex in configuration and represents a relatively costly item in the transmission. Furthermore, the movement typically creates an unbalanced force which induces vibration.
In copending application Ser. No. 083,435, filed Oct. 10, 1979; Ser. No. 077,784, filed Sept. 21, 1979; Ser. No. 077,776, filed Sept. 21, 1979, and Ser. No. 077,656, filed Sept. 21, 1979, there is disclosed an arrangement including a DC drive motor which is commutated so as to be capable of operating in two different modes. In the first mode, there is a cyclically reversing or oscillatory rotation of the output shaft and in a second mode, the motor operates to produce unidirectional rotation of the output shaft.
The use of this type of motor has the advantage when coupled with an appropriate transmission of allowing the elimination of the mechanical movement necessary to produce an oscillatory output, since such movement is directly produced by the motor itself.
A transmission must still be provided even when employing such a drive motor in order to provide the necessary reduction to the basket and impeller and the coupling connections of the motor output shaft to the respective elements, with the motor in its unidirectional rotation mode. A direct drive to the basket must be established since the basket spin is carried out at relatively high rotational speeds equal to the motor output speed.
In the reversing drive mode of the motor, drive is established to the agitator at a rate of rotation much reduced over the rate of rotation of the motor shaft.
Furthermore, the basket itself is preferably braked during agitation such that the basket does not tend to react to the agitation of the wash load which causes it to slowly rotate in the opposite direction and reduce the effectiveness of the washing action.
This latter result arises since the clothing items engage the basket inside surface and are circulated by contact therewith and the agitation of the clothing items would be reduced in the event the basket was allowed to freely rotate in reaction to the agitator motor.
Such transmissions should preferably be of minimum cost, and the shifting arrangement should therefore be relatively simple while being highly reliable, not requiring complex and costly shifting components in order to shift between the neutral, agitation and spin drive conditions of the washing machine.
Also, such transmissions should preferably include a neutral condition in order to enable the drive of the recirculation or drain pumps, without rotation of the agitator or basket.
The transmission furthermore should be properly insulated from the heat of the hot water in the tub since such heat could result in an increased rate of wear of the components.
Also, the gearing and bearing components required to be submerged in oil should be enclosed within a housing of minimum volume.
Another highly desirable feature is the serviceability of the drive arrangement, i.e., the ease with which the unit may be removed from the machine is a major factor relating to the serviceability of the unit by maintenance personnel.
Normally, a mechanical safety brake is applied automatically to the basket, i.e., when the machine lid is open, the drive motor is deenergized and the basket braked to a stop within a short interval in order to minimize the possibilities of accidental injury due to contact with the basket while it is in motion. It would of course be highly desirable it the mechanical brake were not necessitated in order to provide this safety feature. Such mechanical brake would represent a substantial cost item.
Similarly, a mechanical clutch is generally interposed between the drive motor and transmission to enable the motor to develop the full speed prior to completely assuring the load which adds to the cost and complexity of the drive.
Accordingly, it is an object of the present invention to provide a drive arrangement including the above-described type of drive motor which is capable of operating in either an oscillatory or unidirectional drive rotary output mode and which includes a transmission for coupling such drive motor alternately to the washing machine agitator and basket in the respective drive modes.
It is another object of the present invention to provide such transmission which is shifted between neutral, agitate and spin drive modes by a relatively simple and reliable shifter mechanism.
It is still a further object of the present invention to provide such transmission in which there is provided an alternate drive through a gear reduction means in an agitate drive mode, and through a direct drive during the spin drive mode of the drive motor.
It is yet another object of the present invention to provide such gearing which is isolated from the tub in order to insure operation at relatively moderate temperatures and which also includes an arrangement for providing air cooling of the transmission to dissipate the heat generated during the drive cycles.
It is a further object of the present invention to provide an arrangement for using dynamic braking of the drive arrangement without the necessity of employing a mechanical brake which is capable of braking the basket upon deenergization of the drive motor in order to provide the above-described safety feature.
It is still a further object of the present invention to provide an arrangement in which the gearing housing filled with lubricating oil is of minimal volume.
It is still another object of the present invention to provide such transmission in which the basket is restrained against rotation during the agitation cycle.